If you’re a morning person, who jumps out of bed ready to take on the day but feels sluggish by the time afternoon or evening hits, you might think you should do your most creative work at the beginning of the day, when you’re fresh. Likewise, if you’re a night owl, and feel barely awake until mid-afternoon, it’s logical that you’d save your most creative work until late at night.

But a new research study by Mareike Wieth of Albion College and Rose Sacks of Michigan State University finds otherwise (hat tip to the folks over at PsyBlog). The researchers asked 428 students to tackle six problem-solving tasks at different times of day. Those who identified themselves as morning persons actually did better on “insight”-based problem solving—tasks that required original thinking—in the evening. Night owls’ performance was the opposite, with more of their “aha!” moments coming earlier in the day.

Wieth and Sacks hypothesized this would happen, because a key aspect of solving “insight” problems is being able to overcome an impasse in your head. To come up with an original idea or novel solution, in other words, we must be able to approach it from a different perspective. During our “non-optimal” times of day, we’re more influenced by distracting information, and are less blinded by an initial solution that, when we’re more clear-headed, might seem obvious but turns out to be wrong.

In other words, when our brains are “on,” “we’re really good at screening out what we think is irrelevant, and we really get focused on one thing,” says Wieth. “That’s great if you’re doing a task where you have to concentrate, but for creativity that’s probably not the best thing. We get stuck on one way and don’t think of other ways to resolve it.”

That’s not to say that some problems aren’t better solved at our best times of day. Much research, the authors note, has shown that we’re better at concentrating and solving unfamiliar tasks when we’re most “on.” And while Wieth and Sacks do raise the point that their participants were mostly night owls, their results are still worth considering when it comes to productivity and time management. Countless time-management gurus counsel people to tackle their most pressing deadlines first thing in the morning, before they’re interrupted by meetings and phone calls. But if you’re a morning person and your most important job of the day is to come up with a new marketing slogan or dream up a completely new solution to a problem that everyone in your office has already tried to solve, it might actually be better saved until later in the day.

In other words, the best way to manage your time isn’t so much by making yourself do the most pressing thing first, but by figuring out what kind of task it is and then picking the best time to do it. “Is it diffuse thinking or constrained thinking?” Wieth says, as a good rule of thumb. If it’s the former, do it when you’re not as fresh, and if it’s the latter, pick the time when you’re really on.